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Oct 23-06

SP7615 Four Channel Constant Current LED Driver

© Copyright 2006 Sipex Corporation

BLOCK DIAGRAM

Introduction

The SP7615 is a four channel constant current

source LED driver with programmable output

current level. The design consists of a regulator

bandgap, voltage-to-current converter, and

output mirror drivers. The bandgap ensures good

performance over voltage and temperature.

The four outputs are tightly coupled allowing for

excellent channel matching.

Thermal Shutdown

The SP7615 uses a thermal comparator to

monitor the system temperature shutting the

device down if the internal temperature reaches

THEORY OF OPERATION

Figure 1: SP7615 Block Diagram

GND

EN

LED1

LED2

LED3

LED4

Bias

Driver

Thermal

Shutdown

V to I

Converter

Enable

The device has an enable function that is

designed for TTL level inputs. This input will also

track the

V

The enable pin can also be used to control the LED

brightness with a pulse width modulated control

signal. Duty Cycle or PWM control of the LED

current maintains constant LED color while

brightness is changing. The SP7615 responds in

less than 10µs to PWM signals applied to this

pin. The EN pin is internally pulled down with an

approximately 80kOhm resistor. The SP7615 will

remain in shutdown mode if this pin is left open.